Version 2 / simplify extension and move fields to other extensions

[m-mohr]

ESA would like to discuss which fielda of this extension are important to the users / the STAC community and which we might be able to ditch. Also, we want to discuss whether there are better places for some fields that are not overly specific to the mission.
The document where you can leave comments can be found here: https://eoframework.esa.int/display/CDSE/Copernicus+Data+Space+Ecosystem+%28CDSE%29+STAC+catalogue
Alternatively, leave a comment here and I'll move them over to the Confluence page.
Thanks!